The invention relates to elevators generally and, in particular, to an apparatus for the attachment of guide rails to the walls of elevator shafts.
When attaching guide rails for elevators to elevator shaft walls, it must be borne in mind that in buildings, in particular new construction, contractions occur as the masonry subsides and lowers the building height. The guide rails attached to the masonry by means of girders are not subject to such contractions, so that deformations can occur between the clamped parts, which cause a rough running or operation of the elevator car and the counterweight. In the worst case, such contractions can lead to jamming or damage which make the elevator installation unserviceable. The previously described effects also can occur in high-rise buildings due to large temperatures variations, strong wind gusts and seismic forces. Precautions must be taken, therefore, which permit a longitudinal displacement between the guide rails and the masonry of the elevator shaft. For this purpose, attachment devices currently are being used which make possible a displacement of the guide rails in a longitudinal direction and prevent such displacement in a transverse or cross direction.
A device is shown in the U.S. Pat. No. 1,925,867 which is supposed to fulfill the above stated requirements. Iron rail clamps formed of spring steel are bent in a U-shape and have one shorter leg and one longer leg. The shorter leg is solidly bolted to a girder with a spacer sleeve, which girder is attached to the wall of an elevator shaft. The opposite side surfaces of the flange of the guide rail are enveloped by a U-shaped support bracket and which bracket and the flange are pressed against the girder by the longer leg of the rail clamp. The spacer sleeve protrudes through a bore hole in the longer leg such that the longer leg can move freely and apply pressure to the bracket and the guide rail. The U-shaped support brackets, which are held positively by the rail clamps in the longitudinal direction of the guide rail, reduce friction when the guide rail moves relative to the wall of the elevator shaft in a vertical direction.
The device described above has the disadvantage that due to progressive corrosion, the deteriorating surface of the guide rail becomes rough and the free sliding movement in the U-shaped support bracket is rendered difficult or is completely prevented. In order to avoid this, the solidly rusted parts have to be separated from each other and the guide rails be made smooth and lubricated, whereby the upkeep of the elevator installation is made more expensive.
In a mounting of the guide rails shown in the German patent document DE-A 26 46 762, both sides of the flange of the guide rail are enveloped by a single appropriately shaped intermediate plate. Further intermediate plates are provided on the rail clamps and on the mounting plates which are attached in the elevator shaft. The guide rails are held on the mounting plates by the rail clamps while the intermediate plates are pressed on by the sides of the flange. In order to assure a satisfactory shifting or displacement of the guide rails in a vertical direction, a material which exhibits low adhesive and friction coefficients, such as for example Teflon material, is proposed for at least one of the intermediate plates. This solution is expensive with regard to the material and design. Furthermore, Teflon material exhibits creep, so that the intermediate plates deform and have to be replaced frequently, which again raises the maintenance cost of the installation.